DepthTeam Express Fast and easy depth conversion for interpreters R. Sigit DepthTeam Express Fast and easy depth conversion for interpreters R. Sigit

DepthTeam ExpressFast and easy depth conversion for interpreters

R. Sigit

DepthTeam ExpressFast and easy depth conversion for interpreters

R. Sigit

DepthTeam SolutionsOutlineDepthTeam SolutionsOutline

Overview of DepthTeam ExpressOverview of DepthTeam Express

What’s New in the Latest Version?What’s New in the Latest Version?

How does Calibration work?How does Calibration work?

Using DepthTeam Express with Complex VelocitiesUsing DepthTeam Express with Complex Velocities

Using DepthTeam Express with Complex StructuresUsing DepthTeam Express with Complex Structures

Beyond DepthTeam ExpressBeyond DepthTeam Express




















Time Requirements

Time Requirements

AccuracyAccuracy

GeologicComplexityGeologic

Complexity

CostCost

DepthTeam SolutionsWorkflow ContinuumDepthTeam SolutionsWorkflow Continuum

Time Requirements

Time Requirements

AccuracyAccuracy

GeologicComplexityGeologic

Complexity

CostCost

DepthTeam SolutionsWorkflow ContinuumDepthTeam SolutionsWorkflow Continuum

DepthTeamExpress

DepthTeamExpress

DepthTeamExplorer

DepthTeamExplorer

DepthTeamInterpreter

DepthTeamInterpreter

DepthTeamExtreme

DepthTeamExtreme

Construct a velocity model as quickly as possible, using as much data as possible.Construct a velocity model as quickly as possible, using as much data as possible.

DepthTeam ExpressObjectiveDepthTeam ExpressObjective

DetailDetail

Incorporates major sources of velocity informationIncorporates major sources of velocity information

Enhanced IntegrationEnhanced Integration

One data loader for all data typesOne data loader for all data types

Model CalibrationModel Calibration

Vertical depth conversion will tie well control.Vertical depth conversion will tie well control.

DepthTeam ExpressGeneral InformationDepthTeam ExpressGeneral Information

3D Voxcet Velocity Representation3D Voxcet Velocity Representation

Arbitrary X,Y,Z,V velocity cubeArbitrary X,Y,Z,V velocity cube

Seismic Velocities T/D Curves (Checkshot corrected sonic logs)Well Tops

Seismic Velocities T/D Curves (Checkshot corrected sonic logs)Well Tops

Makes data loading simple!

• OpenWorks

• SeisWorks

• EarthCube

• ProMAX

• Sierra

Makes data loading simple!

• OpenWorks

• SeisWorks

• EarthCube

• ProMAX

• Sierra

DepthTeam ExpressEnhanced IntegrationDepthTeam ExpressEnhanced Integration

Workflow ManagersWorkflow Managers

• Model Manager• Model Manager


• Model Manager

• Pick Manager

• Model Manager

• Pick Manager


• Model Manager

• Pick Manager

• Time/Depth Function Manager

• Model Manager

• Pick Manager



• Model Manager

• Pick Manager


• Surface Manager

• Model Manager

• Pick Manager


• Surface Manager


• Model Manager

• Pick Manager


• Surface Manager

• Velocity Cube Manager

• Model Manager

• Pick Manager


• Surface Manager

• Velocity Cube Manager

Incorporates three major sources of velocity informationIncorporates three major sources of velocity information

DepthTeam ExpressData Used to Build Your ModelDepthTeam ExpressData Used to Build Your Model

Data TypeData Type

Seismic VelocitiesSeismic Velocities

Vertical VariationsVertical Variations

AccuracyAccuracy

ContributionContribution

Lateral VariationsLateral Variations

T/D CurvesT/D Curves

Well TopsWell Tops

Each data type makes an important contribution to the final velocity model!

Each data type makes an important contribution to the final velocity model!

DepthTeam ExpressModel Building WorkflowDepthTeam ExpressModel Building Workflow

Seismic VelocitiesSeismic Velocitiesoror

Analytic Velocity ModelAnalytic Velocity Model

Seismic VelocitiesSeismic Velocitiesoror

Analytic Velocity ModelAnalytic Velocity Model

T/D Curve T/D Curve Velocity ModelVelocity Model

T/D Curve T/D Curve Velocity ModelVelocity Model

Well PicksWell Picks Pseudo-velocity ModelPseudo-velocity Model

Well PicksWell Picks Pseudo-velocity ModelPseudo-velocity Model

Calibrated Velocity ModelCalibrated Velocity Model(Seismic Velocities (Seismic Velocities

and T/D Curves)and T/D Curves)

Calibrated Velocity ModelCalibrated Velocity Model(Seismic Velocities (Seismic Velocities

and T/D Curves)and T/D Curves)

Final Calibrated Velocity ModelFinal Calibrated Velocity Model(Seismic Velocities,(Seismic Velocities,

T/D Curves, and T/D Curves, and Well Picks)Well Picks)

Final Calibrated Velocity ModelFinal Calibrated Velocity Model(Seismic Velocities,(Seismic Velocities,

T/D Curves, and T/D Curves, and Well Picks)Well Picks)

Depth ConversionDepth Conversion(TDQ, SeisWorks, EarthCube)(TDQ, SeisWorks, EarthCube)

Depth ConversionDepth Conversion(TDQ, SeisWorks, EarthCube)(TDQ, SeisWorks, EarthCube)

CalibrationCalibrationCalibrationCalibration

CalibrationCalibrationCalibrationCalibration


T/D Curve Velocity Model


Well Picks Pseudo-velocity Model


Calibrated Velocity Model(Seismic Velocities

and T/D Curves)


and T/D Curves)

Final Calibrated Velocity Model(Seismic Velocities,

T/D Curves, and Well Picks)



Depth Conversion(TDQ, SeisWorks, EarthCube)


CalibrationCalibration


Seismic Velocitiesor

Analytic Velocity Model













and T/D Curves)


and T/D Curves)









Load Stacking VelocitiesLoad Stacking Velocities

DepthTeam ExpressSeismic Velocity ModelDepthTeam ExpressSeismic Velocity Model

Constrained Dix InversionConstrained Dix Inversion

DepthTeam ExpressSeismic Velocity ModelDepthTeam ExpressSeismic Velocity Model

Contributes Lateral Velocity TrendsContributes Lateral Velocity TrendsContributes Lateral Velocity TrendsContributes Lateral Velocity Trends











and T/D Curves)


and T/D Curves)









Automatically convert T/D curves to interval velocityAutomatically convert T/D curves to interval velocity

DepthTeam ExpressT/D Curve Velocity ModelDepthTeam ExpressT/D Curve Velocity Model

Use surfaces to structurally interpolate velocitiesUse surfaces to structurally interpolate velocities

DepthTeam ExpressT/D Curve Velocity ModelDepthTeam ExpressT/D Curve Velocity Model

Contributes Vertical Velocity VariationsContributes Vertical Velocity VariationsContributes Vertical Velocity VariationsContributes Vertical Velocity Variations











and T/D Curves)


and T/D Curves)









DepthTeam ExpressWell Picks Velocity ModelDepthTeam ExpressWell Picks Velocity Model

Time Horizons RequiredTime Horizons Required!! Vpseudo = Depth Thickness/ Time Thickness

= Isopach / Isochron

Associate a time horizon with a depth pick.

Isopachs and isochrons are automatically calculated at each well location.

May need to use SynTool to determine time/depth associations.

Time Horizons RequiredTime Horizons Required!! Vpseudo = Depth Thickness/ Time Thickness

= Isopach / Isochron

Associate a time horizon with a depth pick.

Isopachs and isochrons are automatically calculated at each well location.

May need to use SynTool to determine time/depth associations.


Pseudo-velocity ModelPseudo-velocity Model


Contributes Accuracy – Model Ties Well ControlContributes Accuracy – Model Ties Well ControlContributes Accuracy – Model Ties Well ControlContributes Accuracy – Model Ties Well Control











and T/D Curves)


and T/D Curves)









DepthTeam ExpressSeismic Velocity CubeDepthTeam ExpressSeismic Velocity Cube

DepthTeam ExpressT/D Velocity CubeDepthTeam ExpressT/D Velocity Cube

DepthTeam ExpressCalibration: Seismic and T/D VelocitiesDepthTeam ExpressCalibration: Seismic and T/D Velocities

DepthTeam ExpressCalibration: Seismic, T/D, Well PicksDepthTeam ExpressCalibration: Seismic, T/D, Well Picks







and T/D Curves)


and T/D Curves)













DepthTeam ExpressVertical Depth ConversionDepthTeam ExpressVertical Depth Conversion

DepthTeam ExpressConclusionsDepthTeam ExpressConclusions

Easy to learn

Easy to use

May not be appropriate for every situation• High Resolution• Big Data Volumes• Complex Structures

Very useful tool for most situations

Give it a try!

Easy to learn

Easy to use

May not be appropriate for every situation• High Resolution• Big Data Volumes• Complex Structures

Very useful tool for most situations

Give it a try!














DepthTeam Express 1998.6 - What’s New?DepthTeam Express 1998.6 - What’s New?

Highlights:Highlights:

Significant improvements in performance (5x)Significant improvements in performance (5x)- you can now make bigger, more detailed models- you can now make bigger, more detailed models

Stacking Velocity Function Manager Stacking Velocity Function Manager – – you can now see and edit your stacking velocitiesyou can now see and edit your stacking velocities

Consistent use of TablesConsistent use of Tables- data managers, reports, data loading- data managers, reports, data loading- sorting data, selected items to top- sorting data, selected items to top- search, filter- search, filter

Well Pick InterpolatorsWell Pick Interpolators- Linear, First-order, Sierra gridder- Linear, First-order, Sierra gridder

Data StorageData Storage- Everything loaded gets saved – whether it’s used or not- Everything loaded gets saved – whether it’s used or not

Highlights:Highlights:

Significant improvements in performance (5x)Significant improvements in performance (5x)- you can now make bigger, more detailed models- you can now make bigger, more detailed models

Stacking Velocity Function Manager Stacking Velocity Function Manager – – you can now see and edit your stacking velocitiesyou can now see and edit your stacking velocities

Consistent use of TablesConsistent use of Tables- data managers, reports, data loading- data managers, reports, data loading- sorting data, selected items to top- sorting data, selected items to top- search, filter- search, filter

Well Pick InterpolatorsWell Pick Interpolators- Linear, First-order, Sierra gridder- Linear, First-order, Sierra gridder

Data StorageData Storage- Everything loaded gets saved – whether it’s used or not- Everything loaded gets saved – whether it’s used or not














DepthTeam ExpressHow does Calibration Work?DepthTeam ExpressHow does Calibration Work?

Click me.














DepthTeam ExpressWorking with Complex VelocitiesDepthTeam ExpressWorking with Complex Velocities

Complex VelocitiesHard-Rock vs. Soft-RockComplex VelocitiesHard-Rock vs. Soft-Rock

Hard-Rock:Hard-Rock:

The velocity remains the same, regardless of where the rock is.The velocity remains the same, regardless of where the rock is.


Hard-Rock:Hard-Rock:


Cross SectionCross Section

3000 m/sec3000 m/sec


Hard-Rock: Hard-Rock:













































Soft-Rock: Soft-Rock:

The velocity changes, depending on the depth of burial.The velocity changes, depending on the depth of burial.






























1700 - 1800 m/sec1700 - 1800 m/sec





3500 - 4200 m/sec3500 - 4200 m/sec





2250 - 3700 m/sec2250 - 3700 m/sec





1800 - 3900 m/sec1800 - 3900 m/sec





1650 - 4000 m/sec1650 - 4000 m/sec










Soft-Rock Cross SectionSoft-Rock Cross Section







Water BottomWater Bottom


In most areas, the velocity is a combination of hard-rock and soft-rock In most areas, the velocity is a combination of hard-rock and soft-rock Soft-rock near the surface, hard-rock in deeper areas.Soft-rock near the surface, hard-rock in deeper areas.

1650 m/sec1650 m/sec1800 m/sec1800 m/sec









In most areas, the velocity is a combination of hard-rock and soft-rock In most areas, the velocity is a combination of hard-rock and soft-rock Soft-rock near the surface, hard-rock in deeper areas.Soft-rock near the surface, hard-rock in deeper areas.



Soft-RockSoft-Rock

Hard-RockHard-Rock





In most areas, the velocity is a combination of hard-rock and soft-rock In most areas, the velocity is a combination of hard-rock and soft-rock Soft-rock near the surface, hard-rock in deeper areas.Soft-rock near the surface, hard-rock in deeper areas.There may also be small stringers of hard-rock within soft-rock.There may also be small stringers of hard-rock within soft-rock.

Sand ChannelSand Channel


ReefReefSaltSalt

Shale / CoalsShale / Coals




GasGas


In most areas, the velocity is a combination of hard-rock and soft-rock In most areas, the velocity is a combination of hard-rock and soft-rock Soft-rock near the surface, hard-rock in deeper areas.Soft-rock near the surface, hard-rock in deeper areas.There may also be small stringers of hard-rock within soft-rock.There may also be small stringers of hard-rock within soft-rock.Gas can cause strange soft-rock effects!Gas can cause strange soft-rock effects!

GasGas


How do you tell hard-rock from soft-rock?How do you tell hard-rock from soft-rock?

Look at the Well LogsLook at the Well LogsOpenWorks Curve ViewerOpenWorks Curve Viewer

Look at the T/D TablesLook at the T/D TablesDepthTeam Express Function ViewerDepthTeam Express Function Viewer

Hard RockHard Rock

Soft RockSoft Rock

Depth

(m

)D

epth

(m

)

Velocity (m/sec)Velocity (m/sec)

If you see a trend like this on If you see a trend like this on your log curves, be sure to your log curves, be sure to interpret a seismic horizon interpret a seismic horizon associated with this depth!associated with this depth!



DepthTeam Express Function ViewerDepthTeam Express Function Viewer

Tim

e (

ms)

Tim

e (

ms)


Straight-line will not fit data.Straight-line will not fit data.

Why not?Why not?

Complex VelocitiesAnalytic Velocity EquationsComplex VelocitiesAnalytic Velocity Equations

Linear compaction gradient in depthLinear compaction gradient in depth equals EXPONENTIAL compaction gradient in time.equals EXPONENTIAL compaction gradient in time.

Vint = Vo + KZ Vint = Vo + KZ Equation for gradient in depthEquation for gradient in depth

Vint = Vo Exp(KT) Vint = Vo Exp(KT) Equation for gradient in timeEquation for gradient in time

These two equations give the same result! These two equations give the same result!

One is inOne is in depthdepth, one is in, one is in timetime

Complex VelocitiesAnalytic Velocity EquationsComplex VelocitiesAnalytic Velocity EquationsLinear compaction gradient in depthLinear compaction gradient in depth

Vint = Vo + KZ Vint = Vo + KZ Equation for gradient in depthEquation for gradient in depth

Gradient (K):Gradient (K):

Complex VelocitiesAnalytic Velocity EquationsComplex VelocitiesAnalytic Velocity EquationsExponential compaction gradient in time (linear in Exponential compaction gradient in time (linear in depth)depth)Vint = Vo Exp(KT) Vint = Vo Exp(KT) Equation for gradient in timeEquation for gradient in time

Gradient (K):Gradient (K):




Tim

e (

ms)

Tim

e (

ms)



Why not?Why not?

The vertical axis is inThe vertical axis is in TIMETIME, not , not DEPTHDEPTH

An exponential curve will fit the data An exponential curve will fit the data properly.properly.




Tim

e (

ms)

Tim

e (

ms)



Why not?Why not?

The vertical axis is inThe vertical axis is in TIMETIME, not , not DEPTHDEPTH

An exponential curve will fit the data An exponential curve will fit the data properly.properly.

Sometimes these gradients are Sometimes these gradients are misinterpreted!misinterpreted!




Hard RockHard Rock

Soft RockSoft Rock

Tim

e (

ms)

Tim

e (

ms)


If you see a trend like this on If you see a trend like this on your T/D Curves, be sure to your T/D Curves, be sure to interpret this horizon on your interpret this horizon on your seismic data!seismic data!

Exponential curves in Time are Exponential curves in Time are vertical compaction gradients in vertical compaction gradients in Depth.Depth.

Complex VelocitiesModel ResolutionComplex VelocitiesModel Resolution


GasGas


Correct Sampling is Important!Correct Sampling is Important!Bad sampling may cause you to miss important features!Bad sampling may cause you to miss important features!

GasGas



GasGas

Water BottomWater BottomGasGas


Correctly SampledCorrectly Sampled



GasGas



Poorly Sampled Poorly Sampled



GasGas






GasGas






GasGas






GasGas












Correct Sampling is Important!Correct Sampling is Important!Bad sampling may cause you to miss important features!Bad sampling may cause you to miss important features!The objects that are left may be distorted due to under sampling!The objects that are left may be distorted due to under sampling!


This model still ties the wells pretty good, but volumetric estimates will be inaccurate away from well control!



GasGas


Correct Sampling is Important!Correct Sampling is Important!

Correctly SampledCorrectly Sampled

This model ties the wells better, and is more accurate away from the wells.



GasGas


Lateral SamplingLateral SamplingAt leastAt least two grid nodes covering the two grid nodes covering the smallestsmallest velocity feature you velocity feature you want to include in the model.want to include in the model.



Time Horizon - Contour MapTime Horizon - Contour Map

Gas SagGas Sag




Gas SagGas Sag

2000 meters2000 meters



Gas SagGas Sag





Northing: 500mNorthing: 500m

Easting: 1000mEasting: 1000m


Gas SagGas Sag



Easting: 1000mEasting: 1000m


Gas SagGas Sag



Northing: 500mNorthing: 500m



Easting: 1000mEasting: 1000mNorthing: 500mNorthing: 500m


Gas SagGas Sag



GasGas


Vertical SamplingVertical SamplingAt leastAt least two grid nodes covering the two grid nodes covering the smallestsmallest vertical feature you vertical feature you want to include in the model.want to include in the model.


Vertical SamplingVertical SamplingAt leastAt least two grid nodes covering the two grid nodes covering the smallestsmallest vertical feature you want to vertical feature you want to include in the model.include in the model.

Tim

e (

ms)

Tim

e (

ms)


MODELMODEL

T/D CurveT/D Curve

Vertical sampling = 50 msecVertical sampling = 50 msec



Tim

e (

ms)

Tim

e (

ms)


MODELMODEL

T/D CurveT/D Curve




Tim

e (

ms)

Tim

e (

ms)


MODELMODEL

T/D CurveT/D Curve


As vertical sampling decreases, the As vertical sampling decreases, the model comes closer to matching model comes closer to matching the checkshot.the checkshot.

Complex VelocitiesData ProblemsComplex VelocitiesData Problems

Even with correct sampling, you may not observe velocity Even with correct sampling, you may not observe velocity anomalies if they are of limited extent.anomalies if they are of limited extent.

Why?Why?

If the velocity anomaly is not recorded If the velocity anomaly is not recorded somehowsomehow, it will be , it will be impossible to model it!impossible to model it!

• Wells not logged over entire model intervalWells not logged over entire model interval

• Checkshot surveys not recorded from top to bottom of the Checkshot surveys not recorded from top to bottom of the wellwell

• Wells do not penetrate velocity anomaly (gas, sand Wells do not penetrate velocity anomaly (gas, sand channels, etc.)channels, etc.)

• Seismic velocities create the best stack; not the most Seismic velocities create the best stack; not the most accurate velocity modelaccurate velocity model


If you didn’t record it, you can’t model it!If you didn’t record it, you can’t model it!


Gas SagGas Sag

Petronas #1Petronas #1

Petronas #2Petronas #2 Petronas #3Petronas #3

The gas velocity The gas velocity anomaly was not anomaly was not recorded by these recorded by these wells, so the velocity wells, so the velocity model will not include model will not include the gas sag.the gas sag.


If you didn’t record it, you can’t model it!If you didn’t record it, you can’t model it!


Gas SagGas Sag

Petronas #1Petronas #1

Petronas #2Petronas #2 Petronas #3Petronas #3

The gas anomaly can The gas anomaly can be included in the be included in the model, provided that model, provided that thethe model is properly model is properly sampledsampled, and the, and the well well data properly data properly recorded.recorded.Petronas #4Petronas #4

Complex VelocitiesData ProblemsComplex VelocitiesData ProblemsPetronas #4 Well - Two checkshotsPetronas #4 Well - Two checkshots

Tim

e (

ms)

Tim

e (

ms)


Tim

e (

ms)

Tim

e (

ms)


Checkshot recorded Checkshot recorded top to bottomtop to bottom

Checkshot recorded Checkshot recorded only within pay zoneonly within pay zone


Tim

e (

ms)

Tim

e (

ms)


Tim

e (

ms)

Tim

e (

ms)




Top PayTop Pay

T/D tie to top pay is the same in both checkshots.T/D tie to top pay is the same in both checkshots.


Tim

e (

ms)

Tim

e (

ms)


Tim

e (

ms)

Tim

e (

ms)




Top PayTop Pay

Suite of checkshots that all have the same tie at Top Pay.Suite of checkshots that all have the same tie at Top Pay.


Tim

e (

ms)

Tim

e (

ms)



Top PayTop Pay

Suite of checkshots that all have the same tie at Top Pay.Suite of checkshots that all have the same tie at Top Pay.

Which one is right?Which one is right?

How do you know?How do you know?

If you don’t log the entire If you don’t log the entire well, you don’t know which is well, you don’t know which is right!right!


If possible, log the entire borehole.If possible, log the entire borehole.

Typically this is not done, due to high costs.Typically this is not done, due to high costs.

Logging the entire well is less important for the well just drilled, Logging the entire well is less important for the well just drilled, but but veryvery important to build an accurate velocity model for the important to build an accurate velocity model for the next well.next well.

Trends extrapolated from one well can affect the velocity Trends extrapolated from one well can affect the velocity model away from that well. This can change estimated model away from that well. This can change estimated thickness, volumetrics, etc.thickness, volumetrics, etc.

Complex VelocitiesThings to remember…Complex VelocitiesThings to remember…

• Always try to determine if your geologic area is Always try to determine if your geologic area is dominated by hard-rocks or soft-rocks.dominated by hard-rocks or soft-rocks.

• Usually, geologic areas are a mixture of hard and soft Usually, geologic areas are a mixture of hard and soft rock environments.rock environments.

• Young sediments are often soft-rock, old sediments Young sediments are often soft-rock, old sediments are often hard rock. Carbonates are usually hard-rock.are often hard rock. Carbonates are usually hard-rock.

Soft-RockSoft-Rock

Hard-RockHard-Rock

Complex VelocitiesThings to remember…Complex VelocitiesThings to remember…

• If possible, log wells from top to bottom If possible, log wells from top to bottom of the well. of the well.

• If possible, run checkshot surveys from If possible, run checkshot surveys from top to bottom of the well.top to bottom of the well.

• Some velocity effects are difficult to Some velocity effects are difficult to record, but still cause significant record, but still cause significant distortions on the seismic data. Shallow distortions on the seismic data. Shallow gas is especially problematic.gas is especially problematic.

• If possible, try to include as many If possible, try to include as many sources of velocity as you can. sources of velocity as you can.

Tim

e (

ms)

Tim

e (

ms)
















DepthTeam ExpressWorking with Complex StructuresDepthTeam ExpressWorking with Complex Structures

Click me.

It’s easy to tie wells.

The hard part is what happens away from the wells!

Remember:Remember:

All three maps tie the wells - Which one is right? How do you know?

Final Thoughts…CalibrationFinal Thoughts…Calibration

Don’t be tricked into thinking that your model is correct, just because it ties well control!Don’t be tricked into thinking that your model is correct, just because it ties well control!

Important!Important!Important!Important!

All three maps tie the wells - Which one is right? How do you know?

Final Thoughts…CalibrationFinal Thoughts…Calibration

Work on the biggest source of error first. Move on to next biggest source of error ONLY after the most significant source of error has been addressed.

Final Thoughts...Final Thoughts...

Source of error

Am

ount

of

err

or

Interpretation Uncertainty

Velocity Estimation

Depth Conversion Method

Anisotropy

Gridding Errors

Well Deviation Uncertainty

Wavelet Estimation

Well Log Interpretation...

Don’t worry about this...


Source of error

Am

ount

of

err

or


Source of error

Am

ount

of

err

or

… if you haven’t corrected for this.







Beyond DepthTeam ExpressBeyond DepthTeam ExpressZero-offset Ray Tracing with SalimZero-offset Ray Tracing with Salim






Beyond DepthTeam ExpressBeyond DepthTeam ExpressZero-offset Ray Tracing with SalimZero-offset Ray Tracing with Salim

DepthTeam SolutionsBeyond DepthTeam ExpressDepthTeam SolutionsBeyond DepthTeam Express

Salim’s Big Adventure into Ray Tracing! Salim’s Big Adventure into Ray Tracing!

DepthTeam SolutionsValidating 2D DataDepthTeam SolutionsValidating 2D Data

Problem:Problem:

2D Seismic Data can be difficult to interpret.2D Seismic Data can be difficult to interpret.

Reflections often come from out of the plane (sideswipe)Reflections often come from out of the plane (sideswipe)


Problem:Problem:

2D Seismic Data can be difficult to interpret.2D Seismic Data can be difficult to interpret.

Reflections often come from out of the plane (sideswipe)Reflections often come from out of the plane (sideswipe)

Seismic data can have multiple reflections!Seismic data can have multiple reflections!


Ray-trace validate the model using QUIKRAY+Ray-trace validate the model using QUIKRAY+

Solution:Solution:

Use DepthTeam Express to build a modelUse DepthTeam Express to build a model

Ray Tracing in QUIK+Forward ModelingRay Tracing in QUIK+Forward Modeling

Ray Tracing in QUIK+Forward vs. Inverse ModelingRay Tracing in QUIK+Forward vs. Inverse Modeling

Forward ModelingSimulates seismic response of the earth.(Generates synthetic seismic data)Forward

Modeling

Seismic Section

T

Earth Model

Z

Inverse Modeling

Inverse ModelingSimulates the earth from a seismic response.(Generates an earth model in depth)

Ray Tracing in QUIK+Zero offset ray tracingRay Tracing in QUIK+Zero offset ray tracing

Source and receivers are at the same surface location.

Downgoing and upgoing rays follow identical paths.

Ray Tracing in QUIK+Offset ray tracingRay Tracing in QUIK+Offset ray tracing

Source and receivers are not at the same location.

Simulates pre-stack seismic data (shot gathers, CMP gathers, receiver gathers, VSPs, etc.)

Ray Tracing in QUIK+Image RaysRay Tracing in QUIK+Image Rays

Rays shot from surface to reflector.

Rays begin perpendicular to surface.

Simulates time migrated data.

Ray Tracing in QUIK+Normal RaysRay Tracing in QUIK+Normal Rays

Rays shot from reflector back to surface.

Rays begin perpendicular to reflector.

Simulates Stacked (unmigrated) data.

QUIKRAY+Image Ray Tracing simulates poststack time migrated data.

Useful for validating vertical depth conversion (TDQ)

Normal Incidence simulates unmigrated (stacked) data.

Useful for validating quality of 2D seismic lines (sideswipe)

Ray Tracing in QUIK+ModulesRay Tracing in QUIK+Modules

DepthTeam SolutionsBeyond DepthTeam ExpressDepthTeam SolutionsBeyond DepthTeam Express

Salim’s Big Adventure into Ray Tracing! Salim’s Big Adventure into Ray Tracing!

DescriptionDescriptionInterval velocity estimation technique derived from RMS (stacking) velocities.

Vi2= (Vrms22*T2 - Vrms1

2*T1) / (T2 - T1)

AssumptionsAssumptions• CMP gathers follow hyperbolic move-out.• Seismic horizons are flat.• No CDP scatter on CMP gathers. • CMP and CDP are at the same (X,Y) location.• Time maps are zero-offset, UNMIGRATED times.

Velocity Estimation TechniquesDix Inversion


Velocity Estimation TechniquesHyperbolic Moveout

Velocity Estimation TechniquesHyperbolic Moveout

True Seismic Ray Path

=Straight Path Assumed by NMO

2rms

220

2

V

xtt

Velocity Estimation TechniquesNon-Hyperbolic Moveout

Velocity Estimation TechniquesNon-Hyperbolic Moveout

True Seismic Ray Path

=Straight Path Assumed by NMO

2rms

220

2

V

xtt

\

Wave Influenced DeltaWave Influenced Delta

Velocity TypeVelocity Type

Velocity Estimation TechniquesCDP Scatter

Velocity Estimation TechniquesCDP Scatter

Velocity Estimation TechniquesCDP Mispositioning

Velocity Estimation TechniquesCDP Mispositioning

CMPsCMPs

CDPsCDPs

Velocity Estimation TechniquesUnmigrated Times vs Migrated Times


VrmsVrms

TTu

nm

igra

ted

un

mig

rate

d

Unmigrated IntervalUnmigrated Interval



VrmsVrms

TTu

nm

igra

ted

un

mig

rate

d

Migrated IntervalMigrated Interval

Using migrated time maps samples Using migrated time maps samples the Vrms curve at the wrong location the Vrms curve at the wrong location and the wrong thickness.and the wrong thickness.

Amount of incorrect sampling varies Amount of incorrect sampling varies with reflector dip.with reflector dip.

TRUETRUE 1% Error - Vrms21% Error - Vrms2

TimeTime VrmsVrms VintVint VrmsVrms VintVint VerrVerr Depth ErrorDepth Error1.8 2000 2000

3521 3657 3.8% 13.6 meters!2.0 2200 2222



Why is this important?Why is this important?

StrengthsStrengthsFast and easy to calculate.

WeaknessesWeaknesses• Rarely are the assumptions of Dix inversion honored by data.• Very unstable. A 1% error in Vrms can lead to a 3-5% error in Vint.• Using time migrated horizons can easily account for 1% Vrms error!

TRUETRUE 1% Error - Vrms21% Error - Vrms2

TimeTime VrmsVrms VintVint VrmsVrms VintVint VerrVerr Depth ErrorDepth Error1.8 2000 2000

3521 3657 3.8% 13.6 meters!2.0 2200 2222



UseUse• Depth conversion (if properly reduced and calibrated to well velocities).• Depth imaging (do not calibrate to well velocities).

CommentsComments• Vdix values are typically multiplied by scalar of .85 - 1.00 to better match well velocities. Shallow intervals honor Dix assumptions better, and do not require as much reduction as deeper intervals.

• Dix velocities can be useful to understand basic trends in interval velocity, but are typically inaccurate for detailed work.



Documents

DepthTeam Express Fast and easy depth conversion for interpreters R. Sigit DepthTeam Express Fast and easy depth conversion for interpreters R. Sigit